1. Field of the Invention
The invention relates to an electro-chemical sensor such as a corrosion sensor including an array of bismuth nano-wires extending through a chemically inert, non-conductive membrane.
2. Discussion of the Related Art
Methods have been developed that for the fabrication of bismuth nano-wire arrays. Bismuth nano-wire arrays have been grown by electro-deposition on a nano-porous template. Nano-pores are formed in the template by controlled bombardment with swift heavy ions to produce ion tracks. The ion tracks are etched to the desired nano-diameter. The templates have been used to produce arrays of parallel nano-wires that are up to 10 micrometers in length. Etching of the template is controlled so that wires are produced with single nanometer to micron diameters. Density of nano-wires in the array can be varied from about 104 wires/mm2 to 107 wires/mm2.
Nano-porous templates have been fabricated from glass, mica, alumina and polycarbonate polymer. Commercially available nano-porous materials that can be used for templates include porous aluminum oxide (Anopore®), ion-track-etched polycarbonate (Nuclepore®) and ion-track-etched mica.
Detection of corrosion on ship hulls and tanks is of continuing interest in the marine and the admiralty. It is known that paint is not entirely effective in preventing rust from forming on a hull or tank in a corrosive sea water environment. Rust can occur under the paint, undetected prior to forming a blister. Prior to blistering rusting goes on undetected. After blistering, when time permits, the paint is removed and the surface inspected. Pre-blistering paint removal is not usually done on ship hulls and tanks. Also, the quality of any visual inspection is dependent on the thoroughness of the paint removal. It would be desirable to detect insipient rusting under the paint, before blistering and damage occurs. An apparatus for detecting insipient rusting would not achieve wide acceptance if it interfered with the hydrodynamic stream line of the ship hull or added to the acoustic signature of a naval vessel.
Inventors have discovered that the challenge of detecting insipient rusting can be solved by a new electro-chemical sensor.